An <u>autobiography</u> is a retelling of a <u>person's own life</u>. It usually covers most of the experiences and event of the author's <u>childhood</u> until <u>adulthood</u> or present age, and includes personal reflections on how these experiences changed or affect him/her.
On the other hand, a <u>memoir</u> covers a specific period of someone's life that was truly significant.
It depends what that ‘something’ is, if it’s really important then yes, point it out so you don’t forget it later. If it’s something small then there is little to no need to say it
The correct option is D. The statement in option D reveals that the youthfulness which the four old people gained was very momentarily, it soon passed away and they were back to square one.